The most iconic aspect of the Wirtz style is his unconventional and sculptural use of clipped hedges. When Wirtz moved into his current house, he inherited a row of overgrown boxwoods that lined a walk. Too spindly to be trimmed into a rectilinear form, Wirtz followed the natural contours of the branching, creating a pillowy, cloud-like effect. It is this attention to natural form that gives Wirtz’s work its creative edge.
''We love structure,” said Peter Wirtz, “we love to feel firmness.'' Perhaps it’s the firmness of their work that challenges me as a designer and a gardener. Each time I look at their work, I have the same thought: my garden efforts are too small and too timid. But I’m invigorated by the clarity of these gardens. There is no ambiguity about control, no illusions of naturalism. Every effort by the designer is not intended to blur their interventions—like Olmsted in Central Park or Capability Brown at Blenheim—but to declare them. It adds an authenticity to their designs.